This invention relates to a mechanism for coupling two plates. The coupling member used in this coupling mechanism is formed of molded synthetic resin and comprises an umbrella-shaped head portion and two legs extending from the underside of the head portion and each having a stepped engaging portion on the periphery thereof.
In use of a coupling mechanism of this type, the two legs of the coupling member are inserted in elliptical apertures of upper and lower plates, and the head portion of the member is pushed against the upper plate and is rotated by 90.degree., thus causing the stepped engaging portions of the legs to shift from the long-diametric opposing portions of the ellipse aperture of the lower plate to the short-diametric opposing portions of the ellipse and to engage with the short-diametric opposing portions of the ellipse circumference, whereby the two plates are resiliently clamped between the head portion and the stepped engaging portions of the legs. Therefore, in conventional member, it is necessary to align the stepped engaging portions with the short-diametric opposing portions of the ellipse aperture of the lower plate and to keep them in this position. Stated otherwise, if the coupling member is rotated beyond 90.degree., the stepped engaging portions overrun the short-diametric opposing portions of the ellipse aperture, thus releasing the two plates from each other. Therefore, in use a worker must use care to rotate the member by exactly 90.degree. to put the stepped engaging portions in engagement with the short-diametric opposing portions of the ellipse aperture. This requires a careful rotating operation for coupling. Therefore, the work of coupling a large number of plates by means of coupling members of the type mentioned above is tedious and time consuming.
The object of this invention is to provide a coupling mechanism for uniting two plates which is free from the defects mentioned above, permitting automatically regulated and effective coupling work at a high efficiency.